Take a look at this post: http://www.blackberryforums.com/gene...ml#post1283718
That is about the 8900, a device prior to 5.0, written by the same person that created this thread. His remarks are due to the amount of memory on the device.
I would have to agree with him. Many new devices have plenty of memory and there's really no need to follow the steps. However, this all depends on your needs. If you want a ton of apps/themes/etc on your device, then I would follow these steps to give you the memory you need to have those things on your device and still be able to function properly. YMMV.